Can I connect a TV Box to my iMac without HDMI?

If you're asking whether you can use an iMac as a TV set, the answer is No.

The iMac is not a TV set or monitor, and does not accept video input. There are some streaming video services that you can access using a computer, but you cannot plug a set-top cable box or a video game console into an iMac, to display its output on the Mac like you would on a TV set.

greece_pro2013 wrote:

If I use an HDMI to USB adapter will it work?

No. Those are for taking USB-C (DisplayPort) output from a computer and displaying it on a monitor or a TV set that has a HDMI input. They typically are unidirectional – and even if you found an adapter that was bidirectional, the Mac would not accept USB-C (DisplayPort) input.

There are specialized HDMI video capture devices, but many of those cost much more than a TV set – and have the limitation that they do not work with DRM-infested video. The output from a cable TV set-top box is likely to be DRM-infested, and the output from a DVD or Blu-Ray player is guaranteed to be DRM-infested. So you could spend all of that money and still strike out.

If you need a TV, buy one. Large name-brand 4K TVs are very cheap these days. (There are several 43" and 50" Samsung 4K TVs listed on the Best Buy site for $250 or less. I was surprised to find that 32" 4K TVs are hard to find now, presumably because 43" – 55" ones have gotten so cheap.)

+1 No

If your cable TV provider provides internet streaming, then you can use that to watch TV on your iMac.

You're welcome.

FWIW I use my old upgraded 2012 Mac mini, a 32" Samsung TV and FireFox to stream Live TV from my cable TV provider.